Search Publications
Ultraviolet Spectroscopy of Type IIb Supernovae: Diversity and the Impact of Circumstellar Material
Filippenko, Alexei V.; Modjaz, Maryam; Smith, Nathan +9 more
We present new Hubble Space Telescope (HST) multi-epoch ultraviolet (UV) spectra of the bright Type IIb SN 2013df, and undertake a comprehensive analysis of the set of four SNe IIb for which HST UV spectra are available (SN 1993J, SN 2001ig, SN 2011dh, and SN 2013df). We find strong diversity in both continuum levels and line features among these …
Imaging and Spectroscopic Observations of a Transient Coronal Loop: Evidence for the Non-Maxwellian K Distributions
Del Zanna, Giulio; Dudík, Jaroslav; Dzifčáková, Elena +8 more
We report on the Solar Dynamics Observatory/Atmospheric Imaging Assembly (AIA) and Hinode/EUV Imaging Spectrograph (EIS) observations of a transient coronal loop. The loop brightens up in the same location after the disappearance of an arcade formed during a B8.9-class microflare 3 hr earlier. EIS captures this loop during its brightening phase, a…
Broadband X-Ray Properties of the Gamma-Ray Binary 1FGL J1018.6-5856
An, Hongjun; Hailey, Charles J.; Kaspi, Victoria M. +11 more
We report on NuSTAR, XMM-Newton, and Swift observations of the gamma-ray binary 1FGL J1018.6-5856. We measure the orbital period to be 16.544 ± 0.008 days using Swift data spanning 1900 days. The orbital period is different from the 2011 gamma-ray measurement which was used in the previous X-ray study of An et al. using ∼400 days of Swift data, bu…
High Energy Spectral Evolution of V404 Cygni during the 2015 June Outburst as Observed by INTEGRAL
Ubertini, Pietro; Bazzano, Angela; Jourdain, Elisabeth +3 more
The black hole binary GS 2023+338 exhibited an unprecedently bright outburst in 2015 June. On 2015 June 17, the high energy instruments on board INTEGRAL detected an extremely variable emission during both bright and low luminosity phases, with dramatic variations of the hardness ratio on timescales of approximately seconds. The analysis of the IB…
An Off-nucleus Nonstellar Black Hole in the Seyfert Galaxy NGC 5252
Ho, Luis C.; Kim, Minjin; Bianchi, Stefano +6 more
We report the discovery of an ultraluminous X-ray source (ULX; CXO J133815.6+043255) in NGC 5252. This ULX is an off-nuclear point source, which is 22″ away from the center of NGC 5252, and has an X-ray luminosity of 1.5 × 1040 erg s-1. It is one of the rare examples of a ULX, which exhibits clear counterparts in radio, optic…
Self-consistent Castaing Distribution of Solar Wind Turbulent Fluctuations
Perri, S.; Carbone, V.; Sorriso-Valvo, L. +2 more
The intermittent behavior of solar wind turbulent fluctuations has often been investigated through the modeling of their probability distribution functions (PDFs). Among others, the Castaing model has successfully been used in the past. In this paper, the energy dissipation field of solar wind turbulence has been studied for fast, slow, and polar …
A Likely Millisecond Pulsar Binary Counterpart for Fermi Source 2FGL J2039.6-5620
Romani, Roger W.
We have identified an optical/X-ray binary with an orbital period of Pb = 5.47 hr as the likely counterpart of the Fermi source 2FGL J2039.6-5620. GROND, SOAR, and DES observations provide an accurate orbital period and allow us to compare to the light curve of an archival XMM exposure. Like many short-period optical/X-ray binaries asso…
Dynamics of On-disk Plumes as Observed with the Interface Region Imaging Spectrograph, the Atmospheric Imaging Assembly, and the Helioseismic and Magnetic Imager
Krishna Prasad, S.; Pant, Vaibhav; Dolla, Laurent +3 more
We examine the role of small-scale transients in the formation and evolution of solar coronal plumes. We study the dynamics of plume footpoints seen in the vicinity of a coronal hole using the Atmospheric Imaging Assembly (AIA) images, the Helioseismic and Magnetic Imager magnetogram on board the Solar Dynamics Observatory and spectroscopic data f…
Dynamics in Sunspot Umbra as Seen in New Solar Telescope and Interface Region Imaging Spectrograph Data
Yurchyshyn, V.; Kilcik, A.; Abramenko, V.
We analyze sunspot oscillations using Interface Region Imaging Spectrograph (IRIS) slit-jaw and spectral data and narrow-band chromospheric images from the New Solar Telescope (NST) for the main sunspot in NOAA AR 11836. We report that the difference between the shock arrival times as measured by the Mg II k 2796.35 Å and Si IV 1393.76 Å line form…
Pseudostreamers as the Source of a Separate Class of Solar Coronal Mass Ejections
Wang, Y. -M.
Using white-light and extreme-ultraviolet imaging observations, we confirm that pseudostreamers (streamers that separate coronal holes of the same polarity) give rise to a different type of coronal mass ejection (CME) from that associated with helmet streamers (defined as separating coronal holes of opposite polarity). Whereas helmet streamers are…